# Copyright 1999-2020 Alibaba Group Holding Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from collections import OrderedDict
from typing import Any, Callable, Coroutine, TypeVar, Generic


APIType = TypeVar('APIType')


class SessionCache(Generic[APIType]):
    def __init__(self, async_factory: Callable[..., Coroutine[Any, Any, APIType]],
                 cache_size: int = 100):
        self._async_factory = async_factory
        self._cache = OrderedDict()
        self._cache_size = cache_size

    async def create(self, session_id, **kwargs) -> APIType:
        if session_id not in self._cache:
            self._cache[session_id] = await self._async_factory(
                session_id=session_id, **kwargs)
            if len(self._cache) > self._cache_size:
                self._cache.popitem(last=False)
        return self._cache[session_id]
